T-Mobile has just begun offering a new service plan that includes unlimited voice calls, texts, and Wireless Data — including access to this carrier’s 4G network. This plan costs $80 a month, less expensive than comparable plans from competitors.

For comparison, Verizon’s equivalent plan is $120 a month, and Sprint’s is $110. AT&T doesn’t offer a plan with unlimited data, but its “all you can eat” voice and text option with the largest amount of data — 2 GB — is $115 a month.

Not Exactly Unlimited DataThose who are interested in T-Mobile’s new service plan should be aware that while there’s no limit on how much data can be exchanged in each billing cycle, consumers who exceed 2 GB of usage in a billing month will have their data transfer speeds slowed down considerably until their next billing cycle begins.

This is not unusual. Verizon also throttles its customer’s data speeds after they have exchanged a significant amount of data, while AT&T doesn’t offer an unlimited data plan at all. Only Sprint has a completely unlimited data plan.

There are no equivalent limits on customer’s voice calls or texts. T-Mobile’s new service plans apparently allow users to talk as much as they want or send as many text messages as they choose.

Geographic ConsiderationsAnother factor to weigh is that T-Mobile’s cellular-wireless network is primarily concentrated in cities and suburbs. The carrier has relatively weak coverage in rural areas.

The same is true of the rival carrier AT&T, while Verizon’s network is considerably more extensive. Sprint’s network is nearly as large as Verizon’s.

In addition, T-Mobile is still in the process of rolling out its 4G HSPA+ network. It currently reached about 200 million people nationwide. Also, users must have a 4G-capable smartphone to access this high-speed service.